Collimation Eyepiece 31.75 Sky-Watcher

The collimation eyepiece is not an eyepiece in the strict sense of the term. It is a mechanical accessory that fits into the eyepiece holder of binoculars or Newtonian telescopes, and serves to collimate, i.e., align the optics so that they collect light correctly.

Use on a Newtonian Telescope

The technique used with the collimation eyepiece is simple for Newtonian telescopes: by aiming at a uniformly illuminated surface and observing the position of the reflections of the primary and secondary mirrors on each other, it is possible to correctly align the mirrors with each other. The eyepiece is used to place itself just in the optical axis of the instrument and, thanks to its reflective internal surface, it indicates the position of the eyepiece holder in the different reflections.

Use on a Refractor

To collimate binoculars, you must first cover the objective with an opaque hood to avoid any light reflections. Then, place the collimation eyepiece and introduce a light source through the lateral hole of this eyepiece. By looking through the sighting orifice of the eyepiece, you will be able to see the collimation disks reflected on the objective. From then on, it will suffice to superimpose the disks using the collimation screws to have only one.